During WWI, religion was part of the rhetoric of combat. Jenkins noted that people with different faith backgrounds and from different levels of society were all speaking in terms of apocalyptic expectations, angels and Armageddon. In the United States, for instance, pastors would often describe the war as a crusade and the shedding of blood as a kind of holy sacrifice.

Although Jenkins concluded that the war did not lead to an immediate loss in standing for religion in Europe, he highlighted how Christian theologians began to question the way faith had supported such incredible violence.

"World War I does mark a theological revolution," said Jenkins.

Young scholars were horrified that the world's leading theologians from Germany had supported their country's imperial campaign. The next wave of Christian theology, starting with the work of Karl Barth during the war and including many writers who were soldiers themselves, focused on highlighting the Bible's peaceful message of grace and hope.

Willing peace

Campbell can relate to that process of return and revision because the drafts of her WWI commemorative worship resources evolved over time.

Her early efforts focused on the hearts of faithful people. She called for God to move believers' hearts away from desiring war.

But then one of her mentors, acclaimed Old Testament scholar Walter Brueggemann, insisted that she focus not on the heart, but on the human will.

"You need to pray for the will politically, morally and ethically that we will not do these things to one another," Campbell said, quoting Brueggemann. "You need to pray that our politics, our practice of faith, will will peacefulness and will do the things it takes to get there. It's bigger than having the heart for it. You need to have the steel for it and the courage for it and the determination for it."

And even beyond strength, courage and determination, praying for the will to resist violence requires acknowledging the complex relationship between religion and war according to a religion scholar who studies the intersection of theology and war.

"It's never a straightforward case of religion being used to ratchet up the war machine or used to oppose war. The story's a lot more complicated than that," said Jeremy Sabella, who lectures at Yale Divinity School.

Sabella said that for every time religion is appropriated during war times to justify harmful actions there is an example of it serving as a lifeline for people who suffer. "People use religion's language and symbols to (survive) something that threatened them with the abyss of meaninglessness."

Campbell's task was to honor that tension, while calling for peace. "I hope that (the prayers) offer people who have been disturbed by every war a new opportunity to visit in prayer the possibilities of healing, of seeing things new, of committing themselves newly to acts of justice and peace," she said.

And although the WWI anniversary was her inspiration, Campbell had the world's current conflicts in mind as she wrote. "To me, there are a lot of similarities between contemporary warfare and WWI," she said. "In WWI, the technology exceeded the morality."